DESCRIPTION: (Applicant's Abstract) This proposal is for the Pennsylvania College of Optometry (PCO) to serve as one of four clinical centers in the Correction of Myopia Evaluation Trial (COMET). COMET is a prospective, randomized clinical trial designed to assess whether progressive addition lenses (PAL's) slow the progression of juvenile-onset myopia, compared to conventional single vision lenses (SV). Seven hundred fifty children 6-12 years old with myopia (-1.25 to -4.5 D) in both eyes, who meet specific inclusion and exclusion criteria will be enrolled. They will be identified primarily from elementary school vision screenings and School of Optometry clinical patient records. All eligible children will be examined at baseline and at six-month intervals for at least three years to measure changes in refractive error and to update prescriptions. A standardized, common protocol will be used at all four centers. The primary outcome measure is progression of myopia, as measured by cycloplegic autorefraction. An additional outcome measure is axial elongation as measured by A-scan ultrasonography. These will be obtained by masked examiners. This application documents the ability of PCO to screen 7500 children for possible eligibility, to recruit at least 188 children within on academic year, and to retain them for at least three years. Documentation is also provided that PCO has the personnel, equipment, and facilities to conduct the study in accordance with the COMET Manual of Procedures (MOP). Complete details of the COMET rationale, design, and methods are contained in the MOP, which is submitted separately with the Study Chair and Coordinating Center applications. In addition to PCO, the other clinical centers are located at Colleges of Optometry in Boston, Houston, and Birmingham, with the Study Chair in Boston and the Coordinating Center at Stony Brook.